cleaned up specializations of swap()/iter_swap()

[ginac.git] / ginac / ex.h

diff --git a/ginac/ex.h b/ginac/ex.h
index d16bdbc1998c5b31de414f232b42c8e675baa97a..1f4ead98ddf358ab1d3012bb960150e0b0722ce1 100644 (file)
--- a/ginac/ex.h
+++ b/ginac/ex.h
@@ -24,6 +24,7 @@
 #define __GINAC_EX_H__
 
 #include <iosfwd>
+#include <iterator>
 #include <functional>
 
 #include "basic.h"
@@ -89,6 +90,140 @@ public:
         *  Undefined symbols and other parser errors will throw an exception. */
        ex(const std::string &s, const ex &l);
        
+public:
+       // Iterators
+       class const_iterator : public std::iterator<std::random_access_iterator_tag, ex, ptrdiff_t, const ex *, const ex &>
+       {
+               friend class ex;
+
+       public:
+               const_iterator() {}
+               const_iterator(const basic *bp_, size_t i_) : bp(bp_), i(i_) {}
+
+               bool operator==(const const_iterator &other) const
+               {
+                       return bp == other.bp && i == other.i;
+               }
+
+               bool operator!=(const const_iterator &other) const
+               {
+                       return !(*this == other);
+               }
+
+               bool operator<(const const_iterator &other) const
+               {
+                       return i < other.i;
+               }
+
+               bool operator>(const const_iterator &other) const
+               {
+                       return other < *this;
+               }
+
+               bool operator<=(const const_iterator &other) const
+               {
+                       return !(other < *this);
+               }
+
+               bool operator>=(const const_iterator &other) const
+               {
+                       return !(*this < other);
+               }
+
+               // This should return an ex&, but that would be a reference to a
+               // temporary value
+               ex operator*() const
+               {
+                       return bp->op(i);
+               }
+
+#if 0
+               // How do we make this work in the context of the "reference to
+               // temporary" problem? Return an auto_ptr?
+               pointer operator->() const
+               {
+                       return &(operator*());
+               }
+#endif
+
+               const_iterator &operator++()
+               {
+                       ++i;
+                       return *this;
+               }
+
+               const_iterator operator++(int)
+               {
+                       const_iterator tmp = *this;
+                       ++i;
+                       return tmp;
+               }
+
+               const_iterator &operator+=(difference_type n)
+               {
+                       i += n;
+                       return *this;
+               }
+
+               const_iterator operator+(difference_type n) const
+               {
+                       return const_iterator(bp, i + n);
+               }
+
+               inline friend const_iterator operator+(difference_type n, const const_iterator &it)
+               {
+                       return const_iterator(it.bp, it.i + n);
+               }
+
+               const_iterator &operator--()
+               {
+                       --i;
+                       return *this;
+               }
+
+               const_iterator operator--(int)
+               {
+                       const_iterator tmp = *this;
+                       --i;
+                       return tmp;
+               }
+
+               const_iterator &operator-=(difference_type n)
+               {
+                       i -= n;
+                       return *this;
+               }
+
+               const_iterator operator-(difference_type n) const
+               {
+                       return const_iterator(bp, i - n);
+               }
+
+               inline friend difference_type operator-(const const_iterator &lhs, const const_iterator &rhs)
+               {
+                       return lhs.i - rhs.i;
+               }
+
+               reference operator[](difference_type n) const
+               {
+               }
+
+       protected:
+               const basic *bp;
+               size_t i;
+       };
+
+       const_iterator begin() const { return const_iterator(get_pointer(bp), 0); }
+       const_iterator end() const { return const_iterator(get_pointer(bp), bp->nops()); }
+
+#if 0
+       // This doesn't work because of the "reference to temporary" problem
+       // in operator*()
+       typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
+       const_reverse_iterator rbegin() const { return const_reverse_iterator(end()); }
+       const_reverse_iterator rend() const { return const_reverse_iterator(begin()); }
+#endif
+
        // non-virtual functions in this class
 public:
        /** Efficiently swap the contents of two expressions. */
@@ -469,12 +604,6 @@ inline bool is_zero(const ex & thisex)
 inline void swap(ex & e1, ex & e2)
 { e1.swap(e2); }
 
-
-// This makes STL algorithms use the more efficient swap operation for ex objects
-inline void iter_swap(std::vector<ex>::iterator i1, std::vector<ex>::iterator i2)
-{ i1->swap(*i2); }
-
-
 /* Function objects for STL sort() etc. */
 struct ex_is_less : public std::binary_function<ex, ex, bool> {
        bool operator() (const ex &lh, const ex &rh) const { return lh.compare(rh) < 0; }
@@ -588,4 +717,31 @@ inline const T &ex_to(const ex &e)
 
 } // namespace GiNaC
 
+
+// Specializations of Standard Library algorithms
+namespace std {
+
+/** Specialization of std::swap() for ex objects. */
+template <>
+inline void swap(GiNaC::ex &a, GiNaC::ex &b)
+{
+       a.swap(b);
+}
+
+/** Specialization of std::iter_swap() for vector<ex> iterators. */
+template <>
+inline void iter_swap(vector<GiNaC::ex>::iterator i1, vector<GiNaC::ex>::iterator i2)
+{
+       i1->swap(*i2);
+}
+
+/** Specialization of std::iter_swap() for list<ex> iterators. */
+template <>
+inline void iter_swap(list<GiNaC::ex>::iterator i1, list<GiNaC::ex>::iterator i2)
+{
+       i1->swap(*i2);
+}
+
+} // namespace std
+
 #endif // ndef __GINAC_EX_H__